Telephone-exchange system.



E J. L. WRiGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED lULY10,1915.

Patented Oct. 3, 1916.

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WITNESSES: Y nwE/vn J. L. WRIGHT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 10. $915. 1,200,156. Patented Oct. 3,1916.

6 SHEETS-SHEET 2.

WITNESSES: l/Vl/EIVTOR [9m 7lle gwa 5 I MHZ/UM h J. L. WRIGHT. TELEPHONE EXCHANGE SYSTEM.

APPLICATLON FILED JULY 10. 1915.

' Patented Oct. 3,1916.

' 6 SHEETSSH EET 3 INVENTOR WITNESSES:

.I. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED JULY 10. 1915.

1,200,156. Patented Oct. 3,1916.

6 swans-sun 4.

INVENTOR WITNESSES:

did/Mu 1. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLlCATlON FILED JULY 10, 1915.

1,200,156. Patented Oct. 3,1916.

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J O SEPH L. WRIGHT, OF CLEVELAND, OHIO, AS SIGNOB, BY MESNE ASSIGNMENTS, TO JAMES B. GARFIELD, TRUSTEE, OF CLEVELAND, OHIO.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented set. a, rare;

Application filed July 10, 1915. Serial No. 39,100.

To all whom it may concern Be it known that I, JosnPH L. WRIGHT, a citizen of the United States, residing at Cleveland in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a specification.

My invention relates to telephone exchange systems, and especially to that type known as semi-automatic. In systems of this character the lines of the calling subscribers are extended to the lines of the called subscribers by means of automatic switching mechanism. The operation of the switching mechanism is directed by devices under control of operators located at the central exchange. The devices for designating the positions to be assumed by automatic switches and under control of the operators consists of a key-board provided with a plurality of rows of buttons.

One of the features of my invention relates to the manner in which the switches and control devices cooperate so as to insure positive and accurate stepping of the switches. The control device at the operators position consists essentially of a keyboard and associated step-by-step switches.

The main switches used for interconnecting the lines are self-actuated and in stepping transmit impulses to the switches associated with the operators key-board. When the switches associated with the key-board assume positions corresponding to the buttons depressed certain changes are eflfected whereby the automatic switches are brought to rest or made to change their positions as the case may be. In the present instance I have shown the calling subscribers lines terminating on answering jacks located at operators positions. These positions are' equipped with cord circuits with which are associated the key-board and controlling switches.

A co-pending application of mine, Serial No. 766,096, filed May 7 1913, shows the calling subscribers lines connected automatically-to an .operators position or key-board.

The selector and connector switchcircuits and key-board control of the present case could be substituted for the switch circuits and key-board of the copending application to which I have referred.

My invention is illustrated in the accompanying drawings wherein: Figure 1 shows a subscribers line equipment and an operators cord circuit. Fig. 2 shows a first selector switch. Fig. 3 shows a second selector switch, Fig. 4 shows a connector switch and its associated party line selecting switch. Fig. 5 shows a portion of the operators controlling circuit. Fig. 6 shows the operators key-board and stepby step switches associated therewith. Fig. 7 is a modification showing the connections of buttons 8 and 506 combined.

' Referring to Fig. 1, the subscribers station at A comprises equipment usual in common battery systems. The line wires from the subscribers station terminate at an answering jack J and also in multiple termmals 30. These multiple terminals are used by the connector switches when the line is called. The line equipment consists of the usual lin'e relay 1, cut-0E relay 2 and sigseparated by means of the condensers 12 and 13. The calling subscriber is supplied with current for talking through the windings of relay 5 and the retardation coil 4:. Relay 7 is for-connecting the sending device to the calling plug 10.

In Fig. 2 the first selector switch D terminates in a trunk jack JJ. The switch D, as well as the switches E and G of Figs 3 and 4, are of the type shown in Letters Patent 977,536, December 6, 1910, to C. H. North. These switches first rotate in order to bring their wipers in line with the proper rows of contacts and then step vertically to cause the wipers to engage individual contacts in the proper row.

, In Fig. 3 the second selector switch E, instead of terminating in a jack, terminates in multiplecontacts which are engaged by the first selector switch D. The circuits of Figs. 2 and 3 are identical andwill be traced in describing the extension of a connection from a calling to a called subscriber.

In Fig. a connector switch G terminates in the multiple terminals which are engaged in one direction under control'of the step-- Iss , depressing of these buttons at the same inping magnet 481. This switch is caused to restore to its normal position, as shown in Fig. .4, by means of interrupted current, as will be described later. The switch G is also provided with a step-by-step switch M for applying the selected ringing current to the called line at predetermined lntervals.

Referring to Figs. 5 and 6 the rows of buttons 507, 508, 509, 510 and 511 are of the locking and indicating type. When one button of the row is depressed it will restore the button formerly depressed in that row. Each row consists of tenbuttons for transmitting impulses from 1 to 10, depending upon which. button is depressed. The row 50'? is for determining the number of thousands impulses, the row 508 for the hundreds impulses, the row 509 for the tens impulses, the row 510 for the units impulses and the row 511 for the party line impulses. The

switch X steps in unison with the selector and connector switches of Figs. 2, 3 and 4 in proper sequence. selector and connector switches step until the switch X picks out the depressed but tons in the rows. The switch X is used for cutting on the rows of buttons on the keyboard in proper sequence and also determines over which side of the trunk the im pulses are'to be transmitted. The relay 518 is connected to the tip and sleeve conductors by the portion 534 of the switch X This relay 518 is placed in series in sequence with the stepping relays of the selector and connector switches. The operation of the steppingrelays associated with the selector and connector switches causes their respective switches to step. These switches in stepping cause the circuits of their associated stepping relays to be broken, thus interrupting the circuit extending to relay 518. These interruptions cause the operation of relay 518 accordingly and it in turn causes the stopping of the switch X under the influence of the stepping magnet 515. In order to cause the control device and keyboard to become associated with a particular cord circuit the button 506 which is individual to the key-board is depressed at the same time the button 8 associated with the particular cord circuit is depressed. The

stant causes relay 561 (Fig. 5) and relay 7 (Fig. 1) to be placed in series. After these buttons are depressed these relays remain energized in series independent of the con tacts of the buttons 506 and 8.

Fig. 7 shows a modification wherein the depressing of the button 506 is dispensed with. The individual buttons associated with the cord circuits are provided with a set of contacts connected in "multiple to conductor 546 which is shown connected to button 506' in Fig. 6.

Various details of the circuits and appa- This switch and the' ratus will' be described in tracing connection I from a calling to a called subscriber.

The subscriber at station A desiring to call removes his receiver thereby causing the energization of relay 1. The operation of this relay completes the circuit of the signal lamp 3. The operator thereupon answers the call by placing the answering plug 9 into the jack J. The insertion of the plug places relays 2 and 6 in series. The energizing of the former disconnects line relay 1 which in restoring extinguishes the lamp 3. The operation of relay 6 would complete the circuit of the lamp 11, but relay 5 breaks the lamp circuit at this time as it is energized by the closing of the subscribers' tele-' phone circuit.-

The operator pressing the answering but- I button 8 places the winding of relay 7 in series with the winding of relay 561. As

the winding of relay 7 is connected to bat-- tery B it, therefore, follows that these two relays become energized. .After the buttons 8 and 506 are released by the operator, relay 7 and 561 remain energized in series by the following path: battery B, winding of. relay 7, locking contacts of relay 7, 20, 18, winding of relay 561, locking contacts of relay 56.1 to ground through thecontacts of relay 565.

The operation of relay 7 severs the tip and sleeve conductors of the cord circuit and connects the impulse conductors leading to the sending device to the conductors 14 and 16 respectively. The operation of re lay 561 completes the circuit ofthe guard lamp 501. This lamp will remain lighted during the establishment of the connection. The operation of relay 561 connects the control relay 518 (Fig. 6) in series with the stepping relay 122 (Fig. 2) by the following path: ground, contacts of relay 519, 518, 555, portion 534 of the switch X 547, contacts of relay 561, 15, contacts of relay 7 14, 10, JJ, 148, cam springs 127, contacts of relay 123, 146, winding of relay 122 to battery B. The operation of relay 122 closes the circuit of the rotary magnet 120 of the switch D. This magnet in completing its stroke closes the circuit of relay 123 and, consequently,opens that of relays 518 and 122. As soon as the magnet 120 falls back after completing its stroke, the circuit of relay 123 is opened and it in falling back again places relay 122 in series with relay 518. At each opening and closing of the relay circuit 123 the relay 518. is operated. The operation of relays 122 and 518 will continue and the switch X will rotate in unison with the stepping or rotation of the switch D. The

operation of relay 122 also'com letes' the v the release magnet 149.

The circuit of the stepping magnet 515 of the switch X is completed at each stroke of the relay 518 by the following path: ground, contacts of relay 518, 557,- contacts of relay 517 contacts of relay 520,538, 515 to battery B. The switch X and the switch D will continue to step until the wiper of the portion 533 of the switch X reaches a contact leading to the key or buttondepressed in the row 507. As soon as such a contact is reached the circuit of the magnet 512 of the switch X is completed by the following pathz'ground, portion 535 of the switch X 539, depressed button in the row 507, (which we will assume to be the ninth) 529, 533, 537, back contacts of relay 517 556, lorward contacts of relay 518, which is en'- ergized at this instant, 554, 512 to battery B. The closing of the circuit of the magnet 512 causes the switch X to take one step thereby disconnecting relay 518 from the tip conductor and connecting it to the sleeve conductor. As soon as this relay is disconnected from the tip conductor, the circuit of relay 122 (Fig. 2) is broken and the switch D comes to rest with its wipers in line with the ninth row of contacts which corresponds to the ninth button depressed in the'row 507, (Fig. 6). 7

As soon as the switch X takes its'first step, the circuit of relay 517 is closed through the portion 535. This relay operating closes the circuit of relay 520. The operation of this latter relay completes the circuit of relay 519 after relay 518 falls back. Also as soon as the switch X takes the first'step,

relay 518 is placed in series with the test relay 119, (Fig. 2) by the following path: ground, contacts of relay 5 19, 518, 555, 534, 548, contacts of relay 7,16, 10, JJ, v103, cam springs 127, 119 to battery B.. The relays 517 and 518 are thus simultaneously energized. By the time that relay 520 has operated, relay 518 will have accomplished its function and released, thereby establishmg in connection with relay 520 a circuit for relay 519. The operation of relay 518 is only momentary-for as soon as relay 119 becomes energized it looks itself-directly to ground through the back contacts of relay 116, thereby shunting relay 518. Evenif relay 518 does operate, it cannot ailect the stepping magnet 515 as relay 517 is energized thereby opening the circuit of the magnet. The circuit of. the magnet 515, however, is closed by the operation of relay 520 as follows: ground, portion 532 of the switch X contacts of relay 516, 560, contacts of relay 520, 538, 515 to battery B. Magnet 515 in completing its stroke will complete the circuit of relay 516 thereby causing the magnets circuit itself to be opened. The switch X will continue to step and when the permanently grounded contact of the portion 533 is reached, the circuit of ma net 512 of the switch X will be closed as Tollows: ground, 533, 537, contacts of relay 517, 554, 512 to battery; B. The magnet 512 having its circuit closed will cause the switch X to take another step thereby releasing relays 517, 520 and 519 andplace relay 518 again to the tip conductor through the portion 534.

' After the test impulse has been delivered it to the relay 119 and while the switch X is rotating the circuit of the vertical magnet ing path: ground, contacts of relay 116, contacts of relay 119, 118 to battery B. 'Tlie operation of magnet 118 causes the switch D to step vertically and also closes the circuit of relay 116 thereby, breaking the magnet circuit itself. Thecircuit of relay v119 is maintained closed by the wiper 142.engaging busy or grounded contacts and to ground by the following path: ground, contactsof relay 116, locking contacts of 119, winding of 119 to battery B. As soon as the wiper .142 of the switch D engages an idle contact and relay 116 is energized, then the circuit of relay 119 is .no longer maintained and it immediately fallsback, opening the .circuit of the vertical magnet 118, causing the switch D to come to rest with its wipers engaging contacts leading to an idle second selector such as shown in F ig'. 3. While relay 119 is energized, the circuit of relay 117 is closed, the action of this latter relay severs the tip and sleeve conductors while the wipers of the switchD are passing over busy contacts.

It will be noted that even though relay 518 (Fig, 6) is connected to the tip conduc- .completes the circuit of the rotary magnet 166 of the switch E, and the rotary magnet 90 v A 118 of the switch D is closed by the follownaooaac in operating completes the circuit of relay 169, thereby breaking the series circuit be tween relay 162 and relay 518. As soon as the rotary magnet 166 completes its stroke and drops back, then the circuit. of relay 169 is-again broken, allowing relays 162 and 518 to again be placed in series. The vibrating or stepping eiiect between these two relays will continue until the wiper of the portion 533 engages a contact leading to the button depressed in the row 508. We will assume that the second button is the one depressed, whereupon the circuit of the magnet 512 of the switch X will be closed by the following path: ground, 535, 540, second button in the strip 508, 522, 533, 537, back contacts of relay 517, 556, upper contacts of relay 518, 554, 512 to battery B. Magnet 512 having its circuit closed will cause the switch X to take another step, thereby connecting. relay 518 to the sleeve conductor and placing ground to the winding of relay 517. The action of relay 517 completes the its circuit is completed through the winding its circuit of relay 520 as before and when the relay 518 falls back the circuit of relay 519 is closed, preventing any further operation of the relay 518. When the switchX steps and places relay 518 to the sleeve conductor,

of test relay 167, (Fig. 3). The operation of relay 520,. (Fig. 6) allows the circuit of magnet 515 to be closed throu h the portion 532 of the switch X and this switch will 85 continue to rotate as before until the permanently grounded contact ofthe portion 533 is reached, whereupon the circuit of the stepping magnet 512 is completed and the switch X caused to take another step. In taking E40; this step the circuit of the relay 517 is broken and, consequently, the circuit of relays 520 and 519 are opened thereby placing relay 518 again to the tip conductor.-

It after the wiper of the portion 533 of the switch X passes the grounded contact, before the switch E picks out an idle contact, the switch X will come to rest in the position shown in the drawing. (Fig.v 6), as the circuit of the magnet 515 is broken when.

the wiperof the portion 533 reaches its normal position; As soon as the second selector E picks out an idle trunk, the circuit of relay 518 is completed through the wind- .ing of the stepping relay 470 (Fig. 4). While the switch E is stepping vertically, the circuit oi relay 164 is closed and'severs thetip and sleeve conductors to prevent interruption while the wipers of the switch E are passing over busy contactsand also prevents the action of-relay 518, Fig. 6.

As soon as relays 518 and 470, Fig. 4,-are placed in series they will have their circuits opened and closed a number of times corresponding to the button depressed in the party line row 511, Fig. 6. The action of relay 518 causes the switch X? to rotate circuit of the stepping magnet 481 of the switch F by the following path: ground,

contacts of relay 470, 492, contacts of relay 491, 439, 481, 440, contacts of relay 477, 449 to battery B. The operation of relay 470' while the, action of relay 470 completes the also completes the circuit of vrelay 475,

button is reached, the circuit of the magnet 512 of the switch X will be completed b the following path: ground, 535, 543, third button in the stri 511, 523,533, 537,001].- tacts' of relay 517, 556, contacts of relay 518, 554, 512, to battery B. The. operation of the magnet 512 causes the switch X to step, thereby connecting relay 518 to a blank contact and alsocompleting the circuit of relay 517 through the portion 535. The operation of relay 517 now energizes relay 520 which in turn at once energizes relay 519 as the circuit of relay .518 isopened as the wiper of the portion 534 rests on a blank contact. The circuit of the magnet 515 of the switch X will be completed by relay 520 and this switch will continue to step until the grounded contact in the portion 533 is reached, whereupon the circuit of magnet 512 will be completed and, cause the switch X to step. This switch in stepping removes the winding of relay 518 from the blank contact and connects it to the sleeve contact in series with relay 472 (Fig. 4). The switch X in stepping also releases'relay 5'17, 520 and 519. Thecircuits of relays 472 and 518 .will now be opened; and closed a number of times correspondingto the button depressed in the strip 509. The operation of relay 472 completes the circuit cf the rotary magnet 490 by the following path: ground, contacts of relay- 472, cam springs 496, 490 to battery B. The magnet 490, at each stroke, closes the circuit 01? relay 471, thereby opening the circuits of relays 472 and 518. The operation of relay 472 releases relay 475 but closes the-circuit of re lay- 491 by the following path: ground, contacts of relay 161 (Fig; 3), 172, 407, 435, contacts of relay 472, 491, 440, contacts of relay 477, 449 to battery B. The operation lowing path of magnet 512 will be completed by the folground, 535, 541, fourth button in the strip 509, 524, 533, 537 contacts of relay 517, 556, contacts of relay 518, 554, 512 to battery B. The action of magnet 512 causes the switch X to step, thereby breaking the circuits of relays518 and 472, causing the switch G to bring its Wipers in line with thefourth row of contacts in the bank. The shifting of the switch X completes the circuit of the relay 517 which causes the op eration of relays 520 and 519. The circuit of relay 518 is broken as the wiper of the portion 534 comes to rest on a blank contact.

The operation of relay 520 completes the circuit of the magnet 515 causing the switch X to rotate until the wiper of the portion 533 engages the grounded contact whereupon the circuit of magnet 512 is completed,

causing the switch X to step, disconnecting relays 517, 520 and 519 and connecting relay 518 to the tip conductor again in series with relay470, Fig. 4. The operation of relay 470 now closes the circuit of the vertical magnet 489 causing the switch G to step vertically until the wipers engage contacts corresponding to the button depressed in the row 510. The operation of relay 470 also completes the circuit of relay 475 which in turn completes the circuit of relay 479 by the following path: ground, 416, 414, contacts of relay 475, 453, 479 to battery 13. This relay is slow to restore and was also operated the first time relay 475 was energized, but at that time performed no functions. In the present instance, however, the switch G is stepping vertically and the wipers engage contacts of other lines which may be busy. The energizing of relay 479 severs thetlp and sleeve conductors and prevents interference while the wipers are passin over contacts.

When the wiper of the portion 533 of the switch X engages the button depressed in the row 510, which we will assume to be the fifth button, the circuit of the magnet 512 will be completed by the following path: ground, 535, 542, fifth button in the row 510, 525, 533, 537, contacts of relay 517, 556, contacts of relay.518, 554, 512, to battery B. The action of magnet 512 causes the switch X to step disconnecting relays 472 and 518, thereby causing the wipers of the switch G to engage the fifth 5 tact.

set of contacts in the fourth row. The stepping of the switch X places relay 518 to the sleeve conductor in series with relay 472 and also closes the circuit of relay 517. The operation of relay 517 completes the circuit of relay 520 and relay 518' remains energized in series with relay 472, until the switch X takes a step when the circuit of relay 512 is closed by the wiper of the-portion 533 engaging the ounded con- As soon asthis contact is reached, the

the operation of relay 472 connects the test lay of the called line. If the line is busy, relay 47 4 will become energized, but if not, the relay will not be affected. After the test impulse is passed, that is to say when the circuits of relays 472 and 518 are broken, generator current is connected to the called line. c I

Referring again to Fig. 6, assuming the passesthe grounded contact. As soon as this" contact is passed, the wiper of the portion 532 rests in the position as shown, thereby breaking the circuit of the magnet 515 and so, 1 last step has been taken as mentioned, the circuit of the stepping magnet 515 is broken, as soon .as the wiper of the portion 533 completing the circuit of the stepping mag-- net 512 of the switch X in the following manner: As soon as the switch X takes the last step, the circuit of relay 514 is closed to ground through the portion 536 of the switch X The operation of this relay completes the circuit of the magnet 512 by the following path: ground, 532, normal resting contact of the switch X, contacts of.

relay 514, back contacts of relay 513, 512 to battery B. The operation of magnet 512 closes the circuit of the vibrating relay 513 and the operation of relay 513 opens the circuit of the magnet. The action thus set up between the relay and the magnet causes the switch X to be rotated until the circuit of relay 514 is broken, which will happen when the wiper of the portion 536 reaches its normal position.

When the wiper of the portion 536 of the switch X reaches the grounded contacts relay 565 has its circuit completed. This relay in operating removes ground from the locking contact of relay 561, thereby breaking the circuit existing between relays 561 and 7. The latter relay in restoring disconnects the sending device from the cord circuit and closes the tip and sleeve conductors. Relay 561 restoring causes the guard lamp 501 to become extinguished thus notifying the operator that the connection has been established to the line of the called subscriber. I

The ringing circuit is completed after the test impulse has been delivered in the following manner: Relay 476 is placed in series with the cut-ofi relay of the called line through, the wiper 466. The energizing of relay 476 disconnects relay 470 from the tip conductor and closes the circuit of relay 478 by the following path:

ground, contacts 416, 414,-back contacts of relay 475,. 448, forward contacts of relay 491, forward contacts of relay 476, 478 to battery B. The operation of relay 478 completes the circuit of relay 482by the follow mg path: ground, contacts of relay 478, contacts of relay 484, 445, 482 to battery B. The operation of relay 482 connects ground to the winding of the stepping magnet 483 of the switch M. The operation of relay 482 also completes the circuit of the slow relay 418 which in turn com letes the circuit of relay 484. The operation of the latter relay disconnects relay 482, and relay 482 falling back removes ground from the winding of magnet 483and-also from the winding of relay 418. Relay 418 in turn removes ground from the winding of relay 484. A 'ibrating effect is set up between the set of relays 482, 418 and 484, the effect of which causes ground to be connected to and then removed from the winding of the magnet 483, causing it to step and rotate the disks 410-, 400, 415 and 420. At the first step, the disk 410 opens contacts 412 and 413 and closes contacts 412 and 411. At the first step, the disk 400 opens the contacts 461 and 462 and closes contacts 462 and 463. At the first step the disk 415 opens contacts 414 and 416 and closes contacts 416 and 417. As soon as the switch M takes the first step, generator current of the. frequency selected, is connected to the called line and ringing current will be connected to this line until the disks reach their positions as shown in the drawing. Immediately following the ringing period and before the contacts 461 and 462 are closed, the contacts 419 and 421 are closed, energizing relay 498. The operation of this relay opens the circuit of relay- 477 and short circuits the line of the called subscriber thereby removing any charge which may have accumulated on the line. If this provision was not made, then relay 477, especially in case of long lines, would receive a back-kick and prematurely unlock relay 491. r

If the called subscriber removes his receiver during a non-ringing interval, which will be when the disks are in the positions shown on the drawings, relay 477 will be come energized and release relay 491,

-The called subscriber upon hanging up.

his receiver causes relay 477 to fall back, thereby completing the circuit of the stepping magnet 481 of the switch F by the followin path: battery B, 449, contacts of relay 477, 440, 481, 439, contacts of relay 491 492, contacts of relay 475, 437, T, 438 winding of 487, contacts of relay 488, 446,

contacts of relay 477 447, contacts of relay 491, 448, contacts or relay 475, to ground through contacts 414' and 416 controlled by the disk 415. The slow relay 487 in series with the winding of the magnet 481 operates and connects ground directly between its winding and the winding of magnet 481.

495, 441, H, 499, 485, to battery B.

The efiect of this ground causes the mag net 481 to'operate and etc the switch 4 The operation of relay 48 closes the circuit of relay 488 thereby breaking the circuit of magnet 481. After an appreciable length of time, relay 487 falls back and releases relay 488 and the circuit is again closed as previously described. The vibrating action between the relay 487 and 488 and magnet 481 will continue until the wiper of the portion I reaches its normal resting position, thereby breaking the circuit between wires 437 and 438 and preventing further action of the relays and the magnet. As soon as the wiper of the portion I reaches its normal position, the wiper of the portion H engages contact 499 thereby completing the circuit of the. relay 485 by the following path: ground, cam springs The operation of relay 485 closes the circuit of the release magnet 486 causing the switch G to restore and at the same time completes the circuit of relay 479, which in acting severs the tip and sleeve conductors to prevent interference while the switch is restoring. When the switch G reaches its normal position the cam springs 495 are opened and the circuit of relay 485 is broken and consequently that of magnet 486..

The. calling subscriber replacing his receiver opens his line circuit causing relay 5 to restore. The restoration of this relay causes the illumination of the supervisory lamp 11. The operator upon receiving this signal withdraws the plugs 9 and 10 from the jacks J and 5.) respectively. The withdrawing of the plug 9 deenergizes relays 2 and'6. The former relay restoring again connects the linerelay 1 to the line of the calling subscriber. The restoration of relay 6 opens the circuit of the lamp 11.

The withdrawing of the plug 10 removes ground from the test conductor of the switch D thereby causing the deenergization of relay 125. This relay restoring completes the circuit of relay 117 by the following path: cam springs 128, back confacts of relay 125, winding of relay 117 to battery B. The operation of relay 117 severe the tip and sleeve conductors and also completes the circuit of the release magnet 149 by the following path; ground, back contacts of relay 119, contacts of relay 117, winding of magnet 149 to battery B. When the switch D fully restores the cam springs 128 are opened thereby causing the restoration of relay 117. a

As soon as the release magnet 149 of the switch D is operated and the wipers of the switchD leave the contacts of the second selector switch E then ground is disconnected from the test conductor 152, causing the restoration of relay 163. The restoration of this relay completes the circuit of. relay 164 neonate ing ground from the winding of relay 164.

While the switch E is restoring ground is tacts of relays 163 to 152.

connected to ing path ground, cam springs 151, 153, con- Grround being connected in this manner renders the switch .13 busy against other calls until it fully restores and opens the cam springs 151. Incase the called subscriber does not answer the operator withdraws the plugs in the manner just described and causes the release of the switches D and E. The restoration of the switch E removes ground from the .test

- switch, an auxiliary contacts of the connector switch G. causing the restoration of relay 491. The restora tion of this relay eiiects the release of the switch G and its associated parts just as though relay 477 were operated as pre viously described when the called subscriber answers. I

. Having thus described my invention, what I desire to secure by Letters Patent is:

' 1. The combination with an automatic switch, of a stepping-magnet for operating said switch, a primary and a secondary relay associated with said switch, a control device comprising a step-by-step switch, a stepping magnet for said step -by step switch, an auxiliary relay associated with said control device, means for placing the primary relay in series with said auxiliary relay, means controlled by said relays when placed in series for operating the stepping magnets of their respective switches, means controlled by the stepping magnet of-said automatic switch for operating said secondary relay, means controlled by said secondary relay for disabling theprimary and auxiliary relays.

2. The combination 1 with an 7 automatic switch, of a stepping magnet foroperating said switch, a primary and a secondary relay associated'with said switch, a control device comprising a step-by-step switch, a stepping magnet for said step -by step relay associated with said control device, means for placing the primary and auxiliary relays in series, means controlled by said relays when placed in series for operating the stepping magnets of their respective switches, means for operating said secondary relay, means controlled by said secondary relay for disabling the primary and auxiliary relays.

the switch El the primary and auxiliary the test wire'152 by the follow- The combination with an automatic said switch, a primary. and a secondary relay associated With saidswitch, a control de- I i i vice comprising a step-by-step switch,- an

auxiliary relay associated with said control device, means for placing said primary and auxiliary relays in series operation of their respective switch, means controlled by said automatic switch for operating the said secondary relay, means controlled by said secondary relay for disabling relays.

4. The combination with an automatic switch, means for operating said switch, a

device comprising a step-by-step switch,op-

crating means for said step-by-step switch,

means controlled by said relay for intermit- '.tentlydisabling the operating means of both of said switches for the purpose of advancing such switches. 7

'switch,of a stepping magnet for operating u 'wi 1 i for causing the so 1 relay associated with said switch, a control 5. The combination with an automatic switch, means for operatmg said switch, a

relay associated with said I switch, a control device comprising an auxiliary switch, op-

e'ratmg means for said auxiliary swltch,

means controlled by said relay for intermit fi" tentlydisabling the operating means of both of said switches for the purpose of-advancing such switches.

6. The combination with an automatic switch having an associatedrelay, means for,

operatingsa d switch, a controldevice com'- prising an auxiliary switch, means for operating said auxiliary switch, means con- (filed y Said e a for intermittently d f abling the operating means of both of said switches at the same instant for the purpose of advancing such switches.

. 7. Ina telephone exchange system, the

combination with an automatic switch, 111- terrupting means for said switch comprising a stepping magnet, a primary relay for operating said magnet, a secondary relay operated by said magnet for disconnecting said primary relay, anoperators key-board, a control circuit extending between said key-board and said automatic switch, means in saidcontrol circuit 'for disabling said in terru ting means in accordance with the key epressed on said'keyboard.

8. In a telephone exc'iange system, the combination with an automatic switch, selfacting stepping means for said switch, a relay associated with said switch, an oper-- ators key-board comprising a step-by-step switch and an auxiliary relay, a control "circuit extending said automatic switch over which said re-' lays are placed in series, means exercised by said stepping means for causing interruptions in said circuit, said interruptions serving to cause said step-by-step switch to step 1n unison with said automatic switch.

between said key-board and" 9. In a telephone exchange system, the combination with a selector or connector switch, of an operators key-board, an auxiliary switch associated with said key-board, a control circuit extending between the keyboard and the selector switch, and means controlled at the selector switch for interrupting said control circuit, said interrupting means comprising a stepping magnet, a repeating relay for operating said magnet, and a vibrating relay operated by said magnet, said interruptions over the control circuit will continue to cause the stepping of the selector and auxiliary switches until said auxiliary switch picks out the depressed key on said key-board, substantially as set forth. I

10. In a telephone exchange system, the combination with a selector or connector switch, interrupting means for said selector switch comprising a stepping magnet, a repeating relay for operating said magnet, a vibrating relay operated by said magnet to disconnect said repeating relay, of an operators key-board, an auxiliary step-by-step switch associated with said key-board, a-

control circuit extending between said keyboard and said selector switch, and means in said control circuit whereby the interrupting means in said selector switch is disabled when said auxiliary switch picks out the depressed key on said key-board, sub.- stantially as set forth.

In testimony whereof I aiiix my signature in presence of two Witnesses.

JOSEPH" L. wnienr.

Witnesses H.- PoLA'rsEK, A. H. MARTIN. 

